BOCA RATON, Fla. -- Courting the over-65 set in retiree-rich southern Florida Friday, Vice President Joe Biden accused the GOP presidential ticket of planning to poach the Medicare and Social Security tax benefits of the middle class to pay for tax cuts for the wealthy.

"If Governor Romney’s plan goes into effect, it could mean that everyone, everyone of you, would be paying more taxes on your Social Security," Biden told hundreds of retirees at the Century Village community in Boca Raton. "The average senior would have to pay $460 a year more in taxes for their Social Security."

The Obama campaign traces that math to the claim that Romney's tax policy would necessarily require the elimination of some middle-class tax deductions. Using data from the nonpartisan Tax Policy Center, they determine that Romney would have to cut tax benefits for those earning under $200,000 by 58 percent. Spreading those cuts evenly across all benefits would work out to an average of $460 per year per senior.

But Team Romney counters that those numbers are based on a third party's assessment that's riddled with uncertainties and  assumptions rather than Romney's actual plan, which the campaign promises on its website "will not raise [Social Security] taxes and will not affect today's seniors or those nearing retirement."

Republicans also point out that Biden himself voted for a 1993 measure that expanded the taxable portion of Social Security benefits for many low-income seniors.

In Florida Friday, Biden said Romney's tax plan was not "moral" because of what he claims would be unfair hikes on the middle class.

"How can you justify a middle class that has been clobbered by the policies that brought on this great recession, adding taxes to them and drastically cutting taxes for the very wealthy," he told a group made up mostly of seniors in Tamarac. "It's not right, I don't even think it's moral, and beyond that it will not help the economy, it will hurt the economy."

In slamming the GOP ticket, Biden also joked that he can't determine if Romney would actually roll back the Obama-backed health care plan after Romney's on-again off-again embrace of some of its core tenets.

"He said 'well, we’re going to maybe ... do that, but I’d like to keep a lot of the good stuff,' and then his campaign says, 'no no no, he didn’t mean that,' " Biden said.

The vice president, who also won laughs from the elderly crowds for jokes about his age and a Lawrence Welk shout-out that would have sailed over the heads of a younger audience, was warmly received at his campaign events. But he did face persistent questioning on the Obama administration's health care plan when he stopped at Nestor's, a Jewish deli in Boca Raton.

Steve Grossman, a 39-year-old who said he worked in the financial services industry, approached Biden as he sat down to order a tuna salad platter and began asking about health insurance costs. The vice president initially seemed reluctant to answer, cutting Grossman off to order his food and to chat with another patron's husband on the phone, but he ended up offering a description of state-based health care exchanges more fitting for a think tank roundtable than a deli specializing in "the mother of all Pastrami sandwiches."

"You can get more benefits for less money," he told Grossman in between slurps of chicken soup. "You get to choose among those insurance companies that are competing as part of the exchanges."

ZANESVILLE, OH -- The meta-fact check war rages on.

As the campaigns continued to trade salvos over the accuracy of claims made in both parties' convention speeches, Vice President Joe Biden said on Saturday that he's happy to be under the microscope of fact checkers.

Carolyn Kaster / AP

Vice President Joe Biden talks with Lisa McIntosh of Lewisburg, Ohio, as he stops for an ice cream cone Saturday at a Dairy Queen in Nelsonville, Ohio.

"I say to the press, 'Fact check me,'" the vice president declared before launching into a lengthy critique of the Republican plan for Medicare overhaul.

"What they're proposing will actually cost the Medicare trust fund that pays for the benefits when you go to the hospital, the doctor, to run out of money, a sufficient amount of money by 2016," he said. "That's when it would hit the wall."

Biden's claim echoes one made Wednesday night by former President Bill Clinton, who said that the Romney-Ryan goal of repealing the Affordable Care Act would eliminate that bill's measures to keep Medicare solvent until 2024, pushing the date when Medicare will "go broke" up by 8 years.

The non-partisan factcheck.org found that to be an exaggeration; while repeal of ACA would mean the earlier exhaustion of the part of Medicare that covers hospitals, the fund would still collect payroll taxes to cover the vast majority of hospital bills.

The Washington Post put it more bluntly: "This is wrong," it wrote on Sept. 6 of Biden's 2016 Medicare solvency claim.

On Saturday, Biden also accused Republican vice presidential nominee Paul Ryanof proposing to turn the federal health insurance program for seniors into "Vouchercare," saying that the Romney-Ryan plan would raise costs for seniors.

Independent fact checkers have pointed out that while Ryan's most recent budget would provide private insurance vouchers which would grow at the rate of inflation rather than at the rate of health costs, it would also keep traditional Medicare as an option for seniors who wanted it. While most agree that it's likely that seniors would have to pay more if they chose Medicare, it's hard to project how health care costs would change under a hypothetical Romney-Ryan plan.

"Today, Vice President Biden said that he should be fact-checked, and we agree," said Romney spokeswoman Amanda Henneberg. "The vice president knowingly and deliberately leveled false and discredited attacks."

The fact check challenge comes after a Romney pollster was quoted saying that "we're not going to let our campaign be dictated by fact-checkers." Paul Ryan's convention speech was heavily criticized for citing several discredited claims.

Biden poked fun at that sentiment Saturday, calling it "amazing" that the Romney campaign "doesn't like to be fact checked."

Addressing the crowd of about 450 at an Ohio elementary school, Biden also needled Republicans for their impassioned support for Medicare.

"If … you got dropped down from Mars and turned on the convention, you'd think that they really cared about it. You'd think it's something they thought of," Biden said of Republicans.

“They mention it so often you'd be surprised to learn that they've always been trying to chip away [from it] for the last 40 years," he added.

Another fact check? You can't survive on Mars.

Lee Celano / Getty Images

Vice President Joe Biden hands a West Point graduate her a diploma on Saturday.

WEST POINT, NY -- At the graduation ceremony of some of the most elite new members of the U.S. military, Vice President Joe Biden on Saturday praised the Obama administration's efforts to end wars abroad, saying the military drawdowns allow for a "rebalance" of foreign policy.  

Addressing newly minted second lieutenants at West Point's Michie Stadium, Biden spoke at length about the Obama administration's foreign policy achievements: ending the Iraq War, killing Osama bin Laden, and banning torture because "it was the right thing to do."  

"President Obama and I came into office determined to end the war in Iraq responsibly, and today our troops are home," he said.

Highlighting emerging issues like China's economic might and the threat of cyber attacks, the vice president said that the winding down of the Iraq and Afghan conflicts allows the United States more flexibility to address new factors that influence the global landscape.  

"Winding down these long wars has enabled us to replace and rebalance our foreign policy, [to] take on the full range of challenges that will shape the 21st century," he said.  

Among those challenges is the ever-evolving relationship between the United States and China, he said, noting that the two countries don't "always see eye to eye." 

"There's no doubt that America can compete, and America will win whenever and wherever the playing field is level," Biden said.  

Although Biden did not mention the ongoing election fight, he echoed some lines from his past campaign speeches, including a heaping of praise on those who executed the mission to kill Osama bin Laden last year.  

"These warriors sent a message to the world that if you harm America, we will follow you to the end of the earth," Biden said.  

And he referenced the day of the attack masterminded by bin Laden, calling the class of graduates members of a "9/11 generation" that will be remembered as America's greatest.  

"Your generation, the 9/11 generation, is more than worthy of the proud legacy that you will inherit today," he told graduates.